I don’t know anybody who argues that Robert Heinlein’s I Will Fear No Evil is one of his better novels. But, despite pacing issues and a certain lack of action, I enjoyed it the first time I read it, a great many years ago. And, of course, it had a spanking scene, or you wouldn’t be seeing it mentioned here:

He stepped to the wall and squeezed down the intercom to zero, then said gently, ‘Get dressed, dear.’

‘I won’t! If we leave now, you’ll have to stuff me into the car bare naked.’

He sighed and picked her up; she stopped crying and looked suddenly happy.

The expression did not last. He turned her in his arms as he sat down on a straight chair, got a firm grip on her, and walloped her right buttock. She yelped. And struggled.

He got her more firmly, placing his right leg over both of hers, and applied his hand smartly to her left cheek. Then he alternated sides, stopping with ten. He set her on her feet and said, ‘Get dressed, dear. Quickly.’

She stopped and rubbed the punished area. ‘Yes, Jake.’

Neither said another word until he had handed her into the car, climbed in after her, and they had been locked in. Then she said timidly, ‘Jake? Will you hold me?’

‘Certainly, darling.’

‘May I take my robe off, please? Will you take it off me?’

With the robe out of the way she sighed and snuggled in. After a bit she whispered, ‘Jake darling? Why did you spank me?’

It was his turn to sight. ‘You were being difficult … and it is the only thing I know of which will do a woman any good when a man can’t do for her what she needs. And right then – I couldn’t.’

‘I see. I think I do.’

She remained quiet a while, enjoying his arms around her and breathing against his chest.

…

‘Jake?’

‘Yes, Eunice?’

‘I didn’t really mind being spanked by you. Even when I was crying. But — Well, I’m padded now — Built to take an spanking. And when you are spanking me, you aren’t ignoring me — and any attention is better than none. And besides –‘ She hesitated.

‘Besides what, Eunice?’

‘Well, I don’t know — but I think it happened.’

‘What happened?’

‘Female orgasm. Well, maybe. I don’t know what one is supposed to feel like. But while I was crying — and hurting; you have a heavy hand, sir — suddenly I felt very warm inside and something seemed to grow and explode — that’s the best I can describe it. And I was ecstatically happy an didn’t mind the last few wallops, hardly noticed them. Was that a female orgasm?’

Well, being of the male persuasion myself, I’ve never had a female orgasm. But, what Eunice described sure sounds like it could have been one. I hope we’ll hear from some of your female readers on that question.

The reason this novel is one of his weaker ones is that it never underwent final editing. Heinlein finished his first draft, then would up in the hospital sick as a dog for months; his wife and agent decided to publish “as was”.